Some of the Greek philosophers like Pythagoras and Plato understood creation to be based on sound and music, and they used geometry as part of their language. Goethe once said: "Geometry is frozen music."

Sound and music do not have to be physical, traveling through the air etc. You can hear a song in your heart or mind with no physical sound. Music exists in the mind of a composer before it gets written and performed. Therefore this tiangle, and the sound it represents, is still on the spiritual level, which is why the original sound is called the "soundless sound". The closest approximation to this original soundless sound is the OM or AUM.

[link to geometry.wholesomebalance.com]